Quality in tufted pile fabrics, especially carpet, will depend, in part, on the amount of fibers per unit area contained in the pile. Generally, as the carpet fiber count per unit area increases, the attractiveness in both appearance and feel of the carpet increases. Carpet cost, however, also increases as the number of carpet fibers per unit area is increased. As a result, in order to enhance the appearance and feel of tufted pile fabrics, especially carpets, without increasing the number of fibers per unit area and the attendant costs of doing so, it is well known in the art to process such fabrics in order to increase the bulk of the constituent fibers which comprise the pile. The bulked pile resulting from such processing yields the plush appearance and hand of fabrics having greater fiber counts per unit area. As used herein, fiber bulk will refer to the density of fibers per unit volume rather than the fiber count per unit area, and bulking will refer generally to processes which are designed to increase the bulk of fibers.
The methods of bulking tufted pile fabrics known to the art have generally employed steam and the use of beater elements, or alternatively, the application of polymer compositions to the fibers. As described in U.S. Pat. No. 4,301,577--Mueller et al., tufted pile fabrics which have been bent, matted or crushed during processing can be bulked by heating the fabric in a steam chamber by means of the application of steam forced through the backing material and out the face of the fabric, combined with the application of multiple bar beaters to the back side of the fabric. (Mueller et al. col. 2, lines 21-39). The use of steam in such processes, however, presents difficulties as the methods employed to deliver the steam produce variations in the quality and quantity of the steam so applied. These fluctuations lead to an undesirable inconsistency in the degree of fiber bulk thus achieved. Moreover, the resulting article may exhibit an insufficient degree of added bulkiness to justify the use of such processes. The additional bulk imparted to the end product by such methods is often minimal compared to the significant cost of the additional machinery and processing time necessary in the utilization of these methods.
As described in U.S. Pat. No. 5,206,053--Calcaterra, et al., fiber bulk can be enhanced by application of an aqueous solution, emulsion or foam formulation containing a terpolymer comprising phenyl vinyl ether, 2-(4-hydroxymethylphenyl)ethyl vinyl ether and maleic anhydride, or compositions of two copolymers prepared from specific combinations of such monomers. This process, however, is undesirable as the use of polymers or polymeric compositions, whether as solutions, emulsions, foam formulations or otherwise, requires additional processing time and imposes additional costs for materials and chemical expertise, as well as the burdens of various treatment, storage and disposal requirements which may be imposed by applicable environmental regulations.
Applicants have surprisingly and unexpectedly found that the controlled application of dry heat to tufted pile fabric, such as carpet, can increase the fiber bulk thereof uniformly and inexpensively thereby enhancing its appearance and feel to that of more expensive tufted pile fabrics having greater fiber counts per unit area.
It is therefore an object of the present invention to provide a method of bulking tufted pile fabric by means of the controlled application of dry heat.
It is another object of the present invention to provide a method of bulking carpet, and even more preferably solution-dyed tufted carpet, by means of the controlled application of dry heat.
It is still another object of the present invention to provide a method of in-line bulking of tufted pile fabric by means of the controlled application of dry heat.
It is yet another object of the present invention to provide a method of in-line bulking of carpet, and even more preferably solution-dyed tufted carpet, by means of the controlled application of dry heat.